Spark-gap apparatus



Junefs, 1926.

G.D.BAGLEY SPARK GAP APPARATUS Filed Dec. 4, 1922 awww.

Psa-naa .im s, i926.

UNITED STATES PATENT OFFICE.

Gm D. BAGLRY, 0l' ILUSHING, m YORK, ASBIGNOR T0 ELECTRO IITALLUMICAL OOIPANYVA CORPORATION Ol' WEST VIRGINIA.

SPARK-GAP AlPPABATUB.

Appunti@ ma December 4, im. semi No. 604,832.

This invention relates to an improved spark ga apparatus that is especially adapted or use with electric furnaces in which the charge is inductively heated b high frequency electric currents, but it wi l be understood that the improved apparatus may be used with other devices.

In spark gap apparatus heretofore employed in heating circuits for induction furnaces, as more fully disclosed at pages 130, 142, and 146 in a aper by E. F. Northrup, entitled Princip es of inductive heating with high frequency currents published in the Transactions of the American Electrochemical Society, Vol. XXXV, 1919, a transformer, a condenser and the induction winding of a furnace are arranged in circuit with a double spark ga formed by two electrodes spaced from a body of mercury the double gap cooperating with the capacity ,and inductance of such circuit to produce an oscillatory discharge. Such electrodes have heretofore been provided with tips of graphite and copper, which have proven unsatisfactory because the graphite often powders or wears olf and contaminates the mercury electrode, the copper amalgamates with the mercury vapor, and copper vapor condenses on the surfaces of the insulators and forms aI conductive coating that is likely to short circuit parts of the apparatus. According to the present invention tungsten or other suitable highly refractory metal is used as a tip for the electrode that cooperates with the mercury. The tungsten tip resists disintegration for a much longer period than either copper or graphite, and contamination of the mercury is practically avoided.

To reduce the oxidation of the electrodes, alcohol or substances of a similar nature have been introduced into the region surrounding the arc, but the resulting chemical reactions contaminate the mercury. I have discovered that by filling the arc chamber with an atmosphere of hydrogen, oxidation of the electrodes is prevented without contaminating the mercury.

In spark gap apparatus for producing an oscillatory discharge as heretofore constructed the gaps between the mercury electrode and the cooperati electrodes have been varied by raising an lowerin a mercury reservoir communicating with t e spark ga chamber or by using ,movable electrodes siii-ig through @hay seing-poum, The

movable mercury reservoir requires a ilexible connection to the electrode chamber, which is a source of leakage and trouble as are also any sliding parts requiring tight joints. The improved apparatus of this invention embodies a stationary mercury reservoir communicating through rigid pipes with the electrode chamber. A portion of the reservoir is lower than the electrode chamber and a plunger therein may force the mercury from the reservoir into the electrode chamber or allows it to return to the reservoir.

Other advantages and novel features ofn the invention will be apparent from the following description taken in connection with the drawings, in Which- Fig. l is a side view of an improved spark gap apparatus embodying this invention;

Fig. 2 is a plan view of the same; and

Fig. 3 is a vertical sectional view of the same on line 3 3 of the Fig. 2. Referring to the drawings, broadly speaking the present invention comprises two electrodes E and E', which are mounted in separate electrode casings or chambers C and C and are provided at their lower ends with tips T of tungsten `or other conductive highly'refractory material that will resist fusion and disintegration at the temperature of the arc. to form a double spark gap with mercury electrodes M, Min the chambers C, C', and a mercury reservoir R that communicates with the bottoms of these chambers and has part thereof disposed lower than the chambers C, C. The electrodes E, E', are desirably stationary during the operation of the apparatus but the mercury electrodes are adjustable to alter their distance from the tungsten tips welded on the ends of the electrodes E, E. To vary the level of the mercury in the electrode chambers and thereby alter the len th of the double gap, suitable means suc as a plunger P may be movable in the mercury reservoir to force mercury from the reservoir through the communicating passages R into the electrode chambers and to allow the mercury to drain back into the reservoir.

The electrode chambers C, C are connected by a pipe H, so that ysuitable nonoxidizin gas such as hydrogen may be passed t rough both electrode chambers. A cylinder o f compressed hydrogen or lother The electrodes E, E cooperate yfit source of hydro en may be cou led to. an inlet pipe H an 'a seal provided eyond the outlet p1 e H through which the hydrogen may be a owed to lslowly bubble. The electrode chambers C, C', and the reservoir R may be cooled as by enclosing them in a coolino` jacket J having a cover il and water in et and outlet pipes J.

The stationary electrode desirably comprises an outer iron pipe 10 carrying a copper block 11 at its lower end, to the lower face of which a tungsten tip T is welded. The block 11 has a recess or cavity therein to receive the lower threaded end of the pipe 10 and the latter encloses and is spaced from a pipe 12, so that the electrode may be cooled by circulating Water throucli the pipe 12, the recess in the block 11, and the space between the pipes 10 and 12. 'lhe copper block 11 rovides a massive body of goed heat and e ectricity conducting material, and the tungsten tip 'l united thereto cooperates therewith to provide an operating face that greatly prolonge the life of the electrode and prevents excessive formation of copper deposits which have heretofore interfered with the ecient operation of such apparatus. The pipe 10 is threaded'to fit an olpening through the cover 13 from which t e electrode E is suspended, and a fitting F is coupled tothe outer ends'of the pipes 10 and 12 for connectin water pipes thereto. 'lhe upper section o the electrode casing comprises the cover or top 13 and a tubular section 14 of insulating material such as bakelite cemented thereto, which rests in a groove 15 at the upper end of the lower mercury-containing section 16. The section 16 is externally threaded to fit an opening in the cover il of the cooling jacltiet.. rl`he lower edge of the tube 14 rests in the groove 15 which contains suiiicient mercury to seal the joint between the sections of the casing. The head of the electrode casing may thus be readily lifted olf together with tlieelectrode to inspect the latter and the inside of the casing sections.v This construction also provides a safety means to relieve any excessive pressure that might be created in the electrode chambers. Moreover, the pipes H', H" secured to the covers 13 provide means whereby hydrogen may, at will, be supplied to and discharged from the annular spaces around the electrodes and the spaces about the gaps between suoli electrodes and the body of mercury to wash the air out of the electrode chambers after lifting off the upper sections 14, which is occasionally necessary when inspecting, cleaning, or repairing the interior parts. The reservoir R which communicates with the electrode casings through the pipes R is threaded to lit in a hole in the cover J and has a cover 18 threaded to receive the threaded stein 19 of the plunger P which may be lowered and densation of the mercury vapors formed durino the operation of the apparatus and provi e a greater cooli-ng surface so that no part of the apparatus reaches as high a temperature as in the single chamber gap.

By employing the water-cooled tungstentipped electrodes and enclosing the arc space in an atmosphere of hydrogen, I provide an apparatus which is more reliable and requires much less attention than those used heretofore, and the double are gap may be readily adjusted without moving any parts or otherwise disturbing any connections. It will be understood that details of the apparatus shown may be varied without departingfrom the spirit of the invention.

1 claim 1. Spark gap apparatus adapted for use in producing an oscillatory discharge, comprising thecoinbination of a mercury electrode, a massive electrode of good heat and electricity conducting metal having an operating tip of vrefractory metal continuously cooperative with such mercury electrode during the operation of the apparatus, said electrode having a cavity for cooling fluid and means coupled to said cavity for circulating cooling fluid therethrough and means for adjusting said mercury electrode and the other electrode relatively to one another to vary the length of the gap therebetween.

2. Spark gap apparatus for the heating circuit of a high frequency furnace coinprising the combination of a mercury electrode, a water-cooled tungsten-tipped massive copper electrode cooperating therewith, and means for raising and lowering the level of said mercury electrode to adjust it relatively to said cooperating electrode to vary the length of the gap between such electrodes.

3. Spark gap apparatus comprising the combination of a mercury electrode, another electrode cooperating therewith, a casing for said electrodes adapted to contain a nonoxidizing gas, and means whereby non-oxidizing gas may be passed through said casing at will to remove and exclude air therefrom.

4. Spark gap apparatus `comprising the combination of an adjustable mercury electrode, an electrode havin a refractory metal tip cooperating with sai mercury electrode, a casing enclosing the gap between said electiodes and adapted to contain an atmosphere of hydrogen, and means whereby hywith said casing, and means in said reservoir adapted to be operated to adjust the level of the mercury electrode in said casing.

6. Spark gap apparatus comprising the combination of a casing, an electrode in said casing, a mercury electrode in said casing cooperating with the aforesaid electrodeha mercury reservoir communicating with said casing, and a plunger operative on mercury in said reservoir to adjust-the level of the mercury in said casing.

7. Spark ga apparatus comprising the combination o separate intercommunicating electrode chambers adapted to contain hydrogen, cooperating electrodes vin said chambers having spark gaps between them and means whereby h drogen may be passed into and through sai about said gaps.

8. Spark ga apparatus comprising the combination o separate intercommunicating electrode chambers containing hydrogen, electrodes severall arranged in said chambers, and adj ustab e mercury electrode means cooperating with the aforesaid electrodes to provide two spark gaps in series through said mercury electrode means.

chambers and the spaces 9. Spark gap apparatus comprising thecombination of separate electrode chambers, electrodes in said chambers, mercury electrodes in said chambers cooperating with the aforesaid electrodes, a mercury reservoir communicating with said chambers, and means for adjusting the level of the mercury electrodes in said chambers.

l0. Spark gap apparatus comprising the combination of separate electrode chambers, stationary electrodes severally disposed in said chambers, a mercury reservoir communicating with said chambers and containing mercury adapted to enter said chambers and cooperate as electrode means with the said stationary electrodes, and means operative on the body of the mercury in said reservoir t'o adjust the mercury in said chambers relatively to said stationary electrodes.

11. In spark gap apparatus, ythe combination of a casing comprising a container and a cover fastened thereto; a mercury electrode in said casing; a hollow member comprising insulating means carried by and projecting above said cover; means providing an air-excluding joint between said member and said cover; and an electrode comprising water and electricity conducting means extending into said member throu h the top thereof and spaced therefroiuelow said top, and terminal means at the lower end of said conducting means cooperating with said mercury electrode.

12. In spark gap ap aratus adapted for use with furnaces in uctively heated by high frequenc electric currents, the combination of a dy of mercury constituting one electrode; a pair of electrodes cooperating therewith to provide a double spark gap and com rising massive water-cooled blocks of go electricity and heat conducting metal carrying refractory metal tips adapted to cooperate with said body of mercury to provide two spark gaps in series therethrough; means comprising insulating tubes providing annular spaces around such pair of electrodes; and means whereby nonoxidizing gas may be supplied to such annular spaces and the spaces about said gaps to remove air from such spaces.

13. Spark gap apparatus according to claim 11, in which said hollow member comprises a tubular insulating device, and said joint is adapted and constructed to readily permit removal of said device and the electiode therein from said casing without un fastening said cover, and also acts as a. safety means to relieve excessive pressure within said casing.

14. Spark gap appartus comprising the combination of cooperating electrodes, and a casing therefor having a lower section carrying one of said electrodes and an upper section surrounding at least part of the other electrode, said sec-tions having an airexcluding sealed joint there between but being readily separable, such joint comprising a mercury-containing groove in said lower section and said upper section comprising a tubular insulating 'body having `an edge litting in said groove.

15. In spark gap apparatus adapted for use wit furnaces inductively heated by high f equency electric currents, the combination of casing means comprising removable tubes, electrodes disposed in said tubes, adjustable mercury electrode means cooperating with said electrodes to provide two spark gaps in series circuit therewith, and means whereby hydrogen may be supplied to said tubes and the regions about said gaps to remove air-therefrom.

16. Spark gap apparatus comprising the combination of a mercury electrode, anoth` er electrode cooperating therewith, a casing for said electrodes, a mercury reservoir communicating with said casing, mercury in said reservoir adapted to transmit pressure to said mercury electrode to vary the level of the latter, and a cooling jacket enclosing said casing and said mercury reservoir.

17. Spark gap apparatus according to claim 16, in which said jacket comprises a removable cover supporting said casing and said. mercury reservoir.

18. Spark gap apparatus comprising the combination of se arate communicating casings, electrodes 1n said 'casings, mercury electrode means in said casings cooperating with said electrodes, a mercury reservoir communicating with said casings, means for causing the mercury insaid reservoir to adjust the level of the mercury electrode means in said casings, and a cooling jacket iu surrounding said casings and. said reservoir..

ing a tip of refractory metal on one face and a cavity in another face thereof, and means extendin into said cavity for circulating cooling uid therethrough and also for conductin current to said block. said block being etachably connected to said means and adapted to be supported in operative position thereby.

In testimony whereof, I aiix my signature.

GLEN D. BAGLEY. 

